Blind-stitch attachment for sewing machines



Aug. 16, 1938.

J. F. ARVE R BLIND-STITCH ATTACHMENT FOR SEWING MACHINES Filed Nov. 12,1936 2 Sheets-Sheet l [JV VENTOR. 5%

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BLIND-STITCH ATTACHMENT FOR SEWING MACHINES Filed Nov. 12, 1936 2Sheets-Sheet 2 INVEJYJWEI' Patented Aug. 16, 1938 UNITED STATES PATENT,OFFICE BLIND-STITCH ATTACHMENT FOR SEWING MACHINES Joseph 'F. Arver, St.Paul, Minn., ,assignor to Joseph F. Arver and Harold E. Ruttenberg,ccpartners, doing business as Hidstitch Company,

St. Paul, Minn.

Application November 12, 1936, Serial ,No. 110,469

9 Claims.

This invention relates to an attachment for sewing machines and used forthe purpose of .designed for high speeds and silent action in chine,this figure showing the device'in operative position :over the clothplate and adjacent table parts of the sewing machine. Fig. 2 is a frontelevation of, Fig. 1 and showing additionally, in

section, certain feed mechanisms below the cloth plate, as on line 2-2in Fig. 1. Fig. 3 is a left .end elevation of Fig. '2. Fig. 4 is afragmentary view of the outer end portion of a sewing machine table ason line 4-'--4 in Fig. 2, with the cloth plate removed to reveal certaindetails of the stitch length'regulating means. Fig. 5 is an under sideor bottom view as on line 13-43 in Fig. 2 showing certain plungeractuating means of my device. Fig. 6 is ,a sectional detail view as onlined-6 in'Fig.2. Figs. 7, 8 and 9 are diagrammatic top views of thesuccessive needle actions and stitch "forming steps involved in theuseof my device and Fig. 10 is an enlarged sectional view as :on line Ill-lin Fig. 4 and showing additionally apiece of cloth 2, slightly inperspective, being stitched.

' Referring tothe drawings by reference numerals, :l designates thetable or Working surface of a sewing machine and in the outer or leftend part of which stitching is done in cloth 2 fed and moved rearwardlyin direction of arrow 3 (Figs ,"1 and 3) under the presser foot of themachine. 4 is a removably fixed cloth plate in common plane with table1| and which in my device is .of special construction and replaces theregular cloth plate of a sewing machine.

(in Figs. 2 and 3) designates the lower, outer extremity of the sewingmachine head from wh h p ject downwar y e us P $e.r';foot

bar 6 and needle bar I, both reciprocable vertically as in usual sewingmachine structure and. well known in the art, my device utilizing theneedle bar reciprocating action to impart horizontal needlereciprocation in a plane parallel tothe table I and over its cloth plate4. Said needle action provides successive penetrations of the cloth 2the latter being fed across the cloth plate by the usual feed bar 8which reciprocates under the cloth plate, being raised during rearwardmovement for its serrated feed dogs 8D to contact and feed the clothrearward between cloth penetrating actions of the needle. During forwardmovement of the feed dogs and bar'they are lowered and the dogs areinactive until again raised for next cloth moving-step. Said feed bar,the feed dogs-and manipulating means therefor are well known in the artbut herein described and illustrated for the purpose of disclosing theirsynchronized action and relation to various parts of my improved device.I

My device involves aspecial presser foot member comprising an L-shapedplate 9 elongated in direction transversely of the direction of thecloth movement, its Vertical arm comprising in part a socket 9A in thebore of which the lower end of the presser foot bar '6 isremovably'retained as at '9B. I

The vertical part of said presser foot comprises further avertical wallor plate 9B (see Fig. 2) against the front face of which is slidablyengaged a horizontally reciprocable plate Ill by such means as a pair ofbutton-head screws ll or equivalent thereof at the upper edge of plate*IO, other means hereinafter described guiding the lower edge part ofplate It) slidably Where the upright and horizontal plate parts of thepresser foot member converge. The numeral '9 hereinafter designates theelongated lower plate of the presser foot member.

The needle [2 is removably and adjustably fixed parallel and close tothe upper side of plate 9 its point directed toward the left (see Figs.1 and 12) penetrating the cloth 2 which is humped upwardly in the pathof the needle by means of a vertically reciprocable plunger l3 mountedbelow the cloth plate 4 and projectible upwardly therethrough in timedrelation to the needle action, said timed'action of the plunger beingaccomplished by means of the feed bar action as will presently bedescribed. The upper end of the plunger [3 is formed in its left half asa shoulder ISS and is right half rounded downwardly from the diametricaltop edge thus formed, said top edge provided at the middle with a notchI3N traversed by the needle during each cloth penetrating action.

98 (Fig. 2) is a slot in the presser foot plate 9, vertically over theupper end of plunger I3 and so located that the squared shoulder part ofthe plunger is projected upwardly thereinto and projecting the clothupward accordingly over and on the said upper end of the plunger and inthe path of the needle I2 as the presser foot comes down and the needlecomes forward (to the left) and simultaneously penetrates the cloth thusraised in two places, one at each side of the notch of the plunger (seeFigs. 2 and 10). The dash line I2 in Fig. 10 designates the path of theneedle and most clearly shows the. cloth penetrating action.

Subsequently as the needle is withdrawn, during movement to the right,the presser foot 9 is raised by upward movement of the feed dogs 8D theplunger I3 moves down and the feed dogs move the cloth readwardly onestitch length.

The plunger I3 is retained in a bore of a vertically disposed block I4secured at I5 to the under side of my special cloth plate 4 said borebeing enlarged in lowerpartof the block to permit a compression coilspring I6 about the plunger yieldably pressing the plunger downwardly,the plunger extending out of the lower end of the block and itsexposed'lower end continuously and yieldably contacted by a roller I I.Said roller is mounted at the free end of an arm I8 bearing upwardlyyieldablyby means of a spring I 88, the other end of said arm pivotallyconnected at I9 to the lower free end of an inverted L-shaped actuatorlever 20 the upper end of which is pivotally secured at 2I to housingI4. At the elbow of said actuator lever is fixed a roller projection20R, (see Figs. 2, 3 and 5) bearing upwardly and contacting the stempart of a T-shaped cam 22 secured on the under-side of a plate 23 fixedat 24 to the feed bar 8 (see Figs. 2 and 5) and extending in horizontalplane to the left from said bar. This fixed plate 23 is pivotallyconnected at 25 to a lever 26 comprising an elongated flat metal barunder the cloth plate 4 and pivotally connected to the latter near itsouter end on a-pivot 2'! on which it has a limited vertical free action.Said lever 26 extends inwardly, riding freely on top of the feed bar 8(see Fig. 2) and its inner end carries slidably and pivotally, as at 23P(Fig. 4) an integrally formedcloth feeding dog 8D guidingly retained inslots 48 in the cloth plate 4. The lever 26 and its dog 8D are of coursereciprocated by motion of the feed bar 8 through its plate 23 and pivot25 in thelever 26, said pivots 25 and 231? having slidable mounting, topermit straight reciprocating action of the feed dog 8D and plate 23.

The slight vertical freedom, of parts just described, on pivot 21 is toallow the feed dogs to move up and down with the feed fork.

It will now be understood that the cam action of the T-shaped cam 22contacting roller 20R while reciprocating over the latter, provides acertain rise and fall of said roller, which move ment'transmitted tolever 20 causes the latter to swing at its lower end and oscillates theroller I! in vertical plane, the roller in turn raising the plunger I3at correct time for'the cloth penetrating action previously described.Release of said cam contact with roller 20R allows spring I 6 tofunction and pressing the plunger down out of the path of the needle,this taking place and the plunger remaining retracted as the cloth ismoved rearward each step or stitch.

The needle reciprocating means are entirely over or above the clothplate, being actuated directly by the needle bar, which action is ofcourse synchronized with the cloth feeding means described. I will nowdescribe in detail the needle action means.

The reciprocable upright plate I0 is provided intermediate its ends witha diagonal slot IDS engaged by a suitable horizontal projection 28F ofthe block 28 removably secured as at 29 to the lower end part of theneedle bar I. The length of slot IDS, extent of reciprocation of theneedle bar 1, determines the horizontal stroke of plate Ill. The needleis preferably clamped at its heavy end in the horizontal base 308 of anL-shaped bracket 30 the vertical part of which is adjustably retainedfiat against the forward face of plate I0 near its right end, saidadjustable means comprising an'upper eccentric screw 3| and two lower 7screws 32 (see Figs. 1 and 2) the latter passing through slots in thebracket 30. Adjustment of eccentric3I and screws 32 enables an operatorto set the needle accurately or as needed to traverse the notch in theplunger I3. It will be understood of course that the needle point isdirected toward the left.

33 is a thread extending from a spool (not shown) to a tension wheel 34(Fig. 2) on the machine head, thence down to and through an aperture 38Ain clamp 30, thence along the under side of the needle and upthrough itseye (see Figs. 2, '7, 8 and 9). i

35 is a flat metal block fixed transversely on the base plate 9 thisblock being L-shaped and having an arm 35A fixed in parallel relation tothe inner edge and upright part of SE to slidably guide and retain thelower edge of plate I 0 therebetween. The central part of saidtransverse block is in the path of the needle and is notched at itsunder side to permit reciprocation of the needle therein, as at 35N inFig. 6, where an X in L the notch indicates the needle position. Duringstitch forming operations'the needle point is reciprocated through saidblock and past it to the left and under an oscillatable finger plate 36in co-operation with which the needle acts to make and inter-lock threadloops at the left side of the plunger where the needle emerges at eachpenetration.

The loop forming finger plate 36, hereinafter designated the looper isan elongated flat metal plate pivoted on and near the left end of baseplate 9 as at 31 (see Figs. 1, 7, 8 and 9) and directed toward the righttherefrom its latter end formed with a forwardly directed, tapered andsuitably curved finger 36F which is oscillated across the path of theneedle point and said entire finger plate is normally spring pressedrearwardly by any suitable'means such as the wire spring arm 38 fixed ina post 39 on base 9. The looper bears rea'rwardly continuously against acam bar 48 fixed as at 4| on the lower inner face of the slide plateIII, the said bar having a cam shoulder 403 near its right end. Anupright peg 3GP on the looper engages said cam bar and as the plate I0reciprocates the said pin rides the cam bar causing the looper to beoscillated when riding the shoulder 40S, thus oscillating the finger 36Facross-the path of the needleand directly over it. This looper membermay have reciprocating action instead of oscillating or any equivalentthereof.

Assuming now that the needle is about to make a penetration of the cloth2 starting from extreme right position (Fig. 7) the looper 36F is atthis time in extremeiorward position. The

needle first moves to the left to contact the cloth (dotted positionFig. 7) and plunger I3 is upholding the cloth in inverted U or V form inthe path of the needle which penetrates the cloth to the right of theplunger then passes to left in the notch of the plunger anclpierces thecloth alsoin the path of the needle at the left side of said notch. Thisaction brings the needle point, with two bights of thread, out tothe'left as the looper F is moved rearward over the needle as peg 36P atthis instant rides back on shoulder MS of cam bar 40. In Fig. 8 thelooper finger is directly over the needle and in Fig. 9 it is clear ofit rearwardly with its prong directed toward the upper adjacent side ofthe needle. As positioned in Fig. 9 the needle is at extreme leftposition, exposing one bight of the thread on top of the need'le andanother bight under it.

Now when the needle starts back (to right) the thread on top of it ismade slack and finger 3% starting forward enters between said thread andthe needle and as the latter is retracted out of the goods the cloth isfedback one step by the feed bar 8, the finger 36F retains the thread onit in the form of an elongated loop (designated 33L in Figs. 7, 8 and 9)extending from the just completed cloth ,penetrationan'd forward, theforward end of said loop remaining on the finger and becomes slack whenthe looper starts to move back on the shoulder of the cam bar All andsaid loop is penetrated by. the next forward movement of the needle, thesaid thread loop being released from the finger by itsmovee ment to theright caused by the thread of the loop being guided tov the right by theneedle contact and the edge of an aperture 35A in the transverse plate35 and the rearward movement of the cloth by the feed fork. SS is a slotin plate 9 registering vertically with aperture35A just described (seeFigs. 1 and 2).

Thus there are two strands of thread ineach cloth penetration, and onestrand at the right from one penetration to the next,.while on the leftis formed a row of interlocked thread loops 33L in a row parallel to thesingle strands, form ing the blind stitching. l l

The yieldable spring and roller actuated plunger it automaticallycompensates for vary ing thickness of goods passing over the plunger andthe needle in any case penetrates the goods so closely to the undersideof the goods that when the goods are removed from the machine the saidpoints of penetration reveal little or none of the thread on said side.If thread is used of a color similar to the color of the goods thepenetrations are to all intents and purposes invisible, a desirablefeature in certain garment manufacture.

In Fig. 10 a folded hem of a piece of goods 2 is shown in the process ofbeing blind-stitched and illustrating that the looped parts of the blindstitches are completely hidden when the goods are flattened out, and tothe left in said Fig. 10 is shown a row of stitches exposed on a singlethickness of cloth.

My presser foot has a slight vertical action corresponding to that instandard sewing machines and the feed bar and dogs have correspondingfunctions and are timed for proper action as is well known in the art.

In Figs. 2, 3 and 6, 9R designates a transverse rib on the under side ofthe presser foot plate 9 and in proximity to the plunger, this for thepurpose of engaging and alining the goods being stitched in properrelation to the penetrating action or in other words it is an auxiliarymedium for feeding and guiding the goods accurately.

Referring again to the vertically reciprocable plunger I3 and itsyieldable upward pressure, said pressure as described, automaticallyengages any thickness or thicknesses of cloth or various kinds of clothand the correct relative position or location of the notch in theplunger and the needle path therethrough is maintained.

This assures minimum exposure of thread on right side of the goods. Itis clear that upward movement of the plunger brings the angle of itsshoulder directly under the presser foot plate.

It will be readily understood that the stitching action of my device maybe reverse to that shown, or from left to right and other mechanicaldetails within the scope and spirit of my invention may be used.

I claim:

1. A blind-stitch attachment for sewing machines having a verticallyreciprocable presser foot bar and a vertically reciprocable needle bar,

a cloth plate and table in common plane therebelow, a reciprocating feedbar and feed dogs actuated thereby and projectible through the clothplate to contact and feed cloth rearwardly under the needle bar, theaction of said f'e-ed bar synchronized with relation .to the needle bar;said attachment comprising over the cloth plate an elongated presserfoot or" L-shape in cross section and removably fixed on the presserfoot bar, a vertically disposed needle actuator plate slidably retainedin parallel relation to the vertical part of the presser foot, means onthe needle bar for engaging said actuator plate and imparting horizontalreciprocating movement to the said actuator plate, means on saidactuator for adjustably and rigidly retaining a needle in parallelrelation to it, at its base and in proximity to' the presser foot base,meansmounted at the under side of the cloth plate including an uprightplunger projectible, upwardly yieldably in the path of the reciprocatingneedle to press goods to be stitched upwardly in ridge formation overthe cloth plate, said plunger notched cen trally and traversed by theneedle penetrating the goods at both sides thereof, said needle threadedto penetrate the goods with a double big-ht thereof and means mounted onthe presser foot to engage the thread near the point of the needle andform successive interlocked loops of thread in a row on the surface ofthe goods where the needle point emerges.

2. The structure specified in claim 1, said plunger formed at its topend with a shoulder, said presser foot having a slot toward whichv saidshoulder part is projected by the upward movement of the plunger.

3. The structure specified in claim 1, in which said actuator platereciprocating means comprises a block fixed on the lower end of theneedle bar of the sewing machine, said actuator plate being providedwith an inclined slot slidably engaged by said block.

4. The structure specified in claim 1, in which the direction ofreciprocating movement of the needle is transversely of the direction ofthe action of the feed bar and feed dog action of the sewing machine.

5. The structure specified in claim 1, and. an oscillatable cloth-feedlever member pivoted at the underside of the cloth plate near its outerend and extending toward and over the sewing machine feed bar, a feeddog member carried by the free end of said lever said feed dog providedwith serrated parts projectible through and guided in slots provided inthe cloth plate, and a slotted pivotal connection in said feed dog endpart, a plate rigidly secured to the feed bar and having a variablyadjustable pivot connection with said cloth feed lever intermediate theends of the latter, to provide selective feed dog movement for stitchlengths as required.

6. The structure specified in claim 1, and an oscillatable cloth-feedlever member pivoted at the under side of the cloth plate near its outerend, extending toward and over the feed bar, a feed dog member carriedby the free end of said lever, said feed dog provided with serratedparts projectible through and guided in slots provided in the clothplate, and a slotted pivotal connection in said feed dog part with saidlever, a plate rigidly secured to the feed bar and having longitudinallyadjustable pivot connection with said cloth feed lever intermediate theends of the latter, to provide selective movement of the feed dogs, thepivot of said feed dog lever comprising a vertically disposed headed pinlonger than the pivot part of the lever journaled thereon, for thepurpose set forth.

7. A blind-stitch attachment for sewing machines having verticallyreciprocable presser foot and needle bars over a sewing table and clothplate therein, a horizontal and vertically reciprocable feed bar underthe cloth plate and means for synchronizing the feed bar movements withrelation to the needle bar movements; a presser foot secured on thelower end of the presser foot bar, a vertically disposed actuatorslidably retained in said presser foot in proximity to the needle bar,means connecting the needle bar and said actuator to provide horizontalreciprocation of the actuator, a needle holder on said actuator to holda straight needle in horizontal direction and reciprocable accordinglyin a horizontal plane, means for guiding and feeding cloth materialunder said needle on the cloth plate in a direction transverse of theneedle action, plunger means for projecting said material upwardly inthe path of the needle in an inverted V-form to cause double penetrationof the material by the needle and means for retracting said plunger whenthe needle is withdrawn from the material, said needle fixed with itseye vertically directed, thread guide means for thread extending undertension from a source of supply and comprising the provision of avertical aperture in the needle holder for the thread to extenddownwardly therethrough thence longitudinally under the needle andupwardly through its eye to provide a double bight of thread in thepenetrated material, a thread-loop forming finger member manipulated bythe actuator plate to engage a bight of said thread over the needle whenthe latter projects through the material to form a thread loop andretain the same until the needle makes the next penetration, said loopretained in the path of the needle making the next penetration throughsaid loop, and means for releasing said loop from the finger before nextloop forming action.

8. The structure specified in claim 7, in which said loop-forming fingermember comprises a horizontally oscillatable elongated member pivoted onthe presser foot base its free end formed with a transversely arcuate,forwardly directed and tapered finger oscillatable in the path of theneedle and over it to engage the thread on top of the needle as thelatter is positioned thereunder and the finger point is actuatedforwardly.

9. A blind-stitch attachment for sewing machines having verticallydisposed, parallel and reciprocable bars, a horizontal table therebelowand cloth feeding means operating intermittently and in synchronizationwith said bars, a relatively rigid frame mounted on one bar, a needleretaining member slidably mounted in said frame and means mounted on theother bar to produce horizontally reciprocating movement of the needlemember, said latter member comprising in part an adjustable needleholding clamp to hold a needle in horizontal direction over thehorizontal table, means for feeding cloth rearwardly on the table underthe presser foot in successive steps and selective length of movement,and cloth contact means mounted under said table and projectable upwardat predetermined intervals to press the cloth upward in inverted channelshape and in the path of the reciprocating needle to provide doublepenetration of said raised cloth and means mounted on said presser footmember adjacent the extreme forward position of the needle to engage thethread on said needle and form said thread loop during the neXtpenetrating action of the needle.

JOSEPH F. ARVER.

